Did Bestbuy recommend that you buy a USB flash drive or USB hard drive ? If not, go online and buy a flash drive to back up your files. I regularly back up my computer because I know "stuff" happens. So, if my computer were to crash in a big ball of flame, I still have my data.
I encourage EVERYONE to do a back up of their hard drives. Most people don't realize that if their computer dies, they lose all their digital photos. So, if there is anything you don't want to lose, do a back up.
Files can be saved on a "stick" www.amazon.com/SanDisk-Cruzer-Flash-Drive-
or with an external hard drive www.amazon.com/Passport-Portable-External-
These are just examples, there are a lot of different options out there to save your files.